﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information
// 
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 

using System;
using System.Collections;

using log4net.Util;

namespace log4net.Core
{
    /// <summary>
    /// provides method information without actually referencing a System.Reflection.MethodBase
    /// as that would require that the containing assembly is loaded.
    /// </summary>
    /// 
#if !NETCF
    [Serializable]
#endif
    public class MethodItem
    {
        /// <summary>constructs a method item for an unknown method.</summary>
        public MethodItem()
        {
            this.m_name = NA;
            this.m_parameters = new string[0];
        }

        /// <summary>constructs a method item from the name of the method.</summary>
        /// <param name="name"></param>
        public MethodItem(string name)
            : this()
        {
            this.m_name = name;
        }

        /// <summary>constructs a method item from the name of the method and its parameters.</summary>
        /// <param name="name"></param>
        /// <param name="parameters"></param>
        public MethodItem(string name, string[] parameters)
            : this(name)
        {
            this.m_parameters = parameters;
        }

        /// <summary>constructs a method item from a method base by determining the method name and its parameters.</summary>
        /// <param name="methodBase"></param>
        public MethodItem(System.Reflection.MethodBase methodBase)
            : this(methodBase.Name, GetMethodParameterNames(methodBase))
        {
        }

        private static string[] GetMethodParameterNames(System.Reflection.MethodBase methodBase)
        {
            ArrayList methodParameterNames = new ArrayList();
            try
            {
                System.Reflection.ParameterInfo[] methodBaseGetParameters = methodBase.GetParameters();

                int methodBaseGetParametersCount = methodBaseGetParameters.GetUpperBound(0);

                for (int i = 0; i <= methodBaseGetParametersCount; i++)
                {
                    methodParameterNames.Add(methodBaseGetParameters[i].ParameterType + " " + methodBaseGetParameters[i].Name);
                }
            }
            catch (Exception ex)
            {
                LogLog.Error(declaringType, "An exception ocurred while retreiving method parameters.", ex);
            }

            return (string[])methodParameterNames.ToArray(typeof(string));
        }

        /// <summary>
        /// Gets the method name of the caller making the logging 
        /// request.
        /// </summary>
        /// <value>
        /// The method name of the caller making the logging 
        /// request.
        /// </value>
        /// <remarks>
        /// <para>
        /// Gets the method name of the caller making the logging 
        /// request.
        /// </para>
        /// </remarks>
        public string Name
        {
            get { return this.m_name; }
        }

        /// <summary>
        /// Gets the method parameters of the caller making
        /// the logging request.
        /// </summary>
        /// <value>
        /// The method parameters of the caller making
        /// the logging request
        /// </value>
        /// <remarks>
        /// <para>
        /// Gets the method parameters of the caller making
        /// the logging request.
        /// </para>
        /// </remarks>
        public string[] Parameters
        {
            get { return this.m_parameters; }
        }

        private readonly string m_name;
        private readonly string[] m_parameters;

        /// <summary>The fully qualified type of the StackFrameItem class.</summary>
        /// <remarks>
        /// Used by the internal logger to record the Type of the
        /// log message.
        /// </remarks>
        private static readonly Type declaringType = typeof(MethodItem);

        /// <summary>
        /// When location information is not available the constant
        /// <c>NA</c> is returned. Current value of this string
        /// constant is <b>?</b>.
        /// </summary>
        private const string NA = "?";
    }
}
